I have tried this in the past and its incredible how much different even walking with a locked in ankle is.
https://www.youtube.com/watch?v=HvQnEXGdMaA
The locking of the ankle instantly activates the glutes. You can feel the glutes and feel how its freeing up your thighs. Its true!
I found it!
Real interesting guy to follow!
https://www.youtube.com/watch?v=pA4qaCd5JbA
The book is The secret of athleticism
Its more the locking of the ankle and not necessarily the toes
Also talks about the myth of squeezing butt cheek activating the glutes!
There a ton of articles on this. There s one guy in particular and I'm almost positive this is where you are getting this info from. I cant remember his name , Can you share?